Effects of statistical fluctuations in a model of tropospheric chemistry

We present numerical simulations of the ozone concentration in the troposphere based on a six-variable model of tropospheric chemistry. Although the model is not meant to describe the detailed mechanism of tropospheric chemistry it contains nonlinear steps leading to oscillatory behaviour. Statistical noise imposed upon the emission intensity of nitric oxide may lead to the interesting phenomenon of internal signal stochastic resonance. Here the imposed noise amplifies oscillatory dynamics of the system under conditions which lead to a stable stationary state in the absence of noise. A combination of statistical perturbations with a slow modulation of the rates of photosensitive steps allows to qualitatively reproduce observed time series of the ozone concentration.